Generics，

Generics，

http://docs.oracle.com/javase/1.5.0/docs/guide/language/foreach.html


http://docs.oracle.com/javase/1.5.0/docs/guide/language/generics.html#expurgat


Note that unboxing occurs when the expression it.next() of type Inte
ger is assigned to the variable n of type int.